Multi-beam convergence circuits



ay 13, 1958 M. D. NELSON MULTI-BEAM coNvERGENcE CIRCUITS 2 Sheets-Sheetl Filed Oct. 5, 1955 E m Vl M x w w j Z F. i Wr, n www mm f f www wwwma, 5 7l MMM :VWO www 2 Z k MP wm 0D. 0 wm M W N O S L E N D. M.

MULTI-BEAM CONVERGENCE CIRCUITS 2 Sheets-Sheet 2 Filed OO'C. 3, 1955 INVEN TOR. v n f s F www ZI,834,91 l Patented May 13, 1958 tice MULTI-BEAMcoNvnnGnNcE cincuirs Morris D. Nelson, New York, N. Y., assignor toRadio Corporation of America, a corporation of Delaware ApplicationOctober 3, 1955, Serial No. 539,883

9 Claims. (Cl. 315-13) The invention relates to systems for controllingthe deection of electron beams of cathode ray tubes, and it particularlypertains to such systems in which a plurality of electron beams aredeected by common deflection circuitry.

One type of cathode ray tube, or kinescope with which the invention maybe successfully used is a color kinescope of the general type describedin an article A Three-Gun Shadow-Mask Color Kinescope, by H. B. Lawpublished in the Proceedings of the IRE, volume 39, No. l0, for October1951 at page 1186. Part of the target electrode structure of such a tubeis a luminescent screen in which different phosphor areas producedifferently colored light when excited by electron beams impinging fromdifferent angles, the angle of impingement determining the particularcolor of the light produced. For satisfactory operation of suchkinescopes, it is necessary to effect substantial convergence of thedifferent electron beams at all points on the raster formed bydeflecting the three electron beams in two mutually perpendiculardirections. A general discussion of this beam convergence problem willbe found in an article entitled Deection and Convergence in ColorKinescopes, by A. W. Friend, published in the Proceedings of the IRE,volume 39, No. l0, for October 1951 at page 1249. One type of multi-beamkinescope to which the invention particularly pertains includes a pairof magnetic pole pieces for each beam located internally of thekinescope envelope. These internally located pole pieces are energizedby magnetic components arranged outside the kinescope envelope. Thesemagnetic components may be entirely electromagnetic or they may includesome permanent magnetic structure since the internally located polepieces usually require static as well as dynamic energization. Ingeneral, it is desirable to provide such convergence means forkinescopes with the minimum of additional components.

An object of the invention is to provide improved circuitry foreffecting convergence of the plurality of electron beams of a multi-beamkinescope.

Another object of the invention is `to provide an improved circuitry foreffecting convergence of the plurality of beams of a multi-beamkinescope with passive network elements.

According to the invention parabolic convergence current waves forapplication to the pole-piece exciting windingsV of .a multi-beamkinescope are obtained by integration of pulse and sawtooth voltagewaves in resistive and inductive reactance circuits. The circuitfeatures ,adjustable resistance elements connected in the cathode lead`of a vertical deflection wave amplifying tube which in conjunction withan inductance element provides variable amplitude parabolic voltagewaves at the vertical deflection rate which are integrated uponapplication to the highly inductive convergence system windings to causecurrents of parabolic Waveform to flow therethrough. Other resistiveelements connected ,across a center-tapped isolated winding on avertical deection wave transformer provide variable amplitude positiveor negative sawtooth voltage waves at the vertical deflection rate fortilting the parabolic waves. A voltage pulse obtained from a horizontaldeflection wave amplifying circuit is applied to a plurality of seriescircuits each comprising an adjustable inductance element and aresistance element of low impedance with respect to that of theinductance element. The amplitude of the sawtooth voltages thus producedat the horizontal line deflection rate may be adjusted by varying theinductances in the circuits to provide variable amplitude current wavesat horizontal deiiection rate of parabolic waveform upon applicationsawtooth voltages to the highly inductive convergence system windings. Acompensating capacitance element may be interposed in series with eachresistance element to provide more suitable waveform and also in orderto reduce the power loss by permitting the use of larger values ofresistance elements. The resulting parabolic current waveform iscorrected for tilt by adding a sawtooth current wave of horizontaldeflection rate to the parabolic wave. Another capacitive reactanceelement is connected between the junction of the compensatingcapacitance element and the resistance element and the point at whichthe horizontal voltage pulse is applied to the inductance element. Thetwo capacitive elements form a capacitive voltage divider. The othercapacitance element may be adjustable in order to vary the amplitude ofthe sawtooth component which is added for tilting the parabolic wave. Bymeans of a trilar winding, interposed in the circuit to prevent thehorizontal deflection rate currents from llowing in the verticaldeection Wave circuits whose impedance is normally of a low value atwhich the horizontal frequency components would be excessively loaded,both horizontal and vertical convergence current waves ow in the samewindings, The use of a tritilar winding effectively isolates theseparate convergence circuits and also insures that the horizontal ratevoltage pulses are initially of the same value in each of theconvergence circuits despite variations in the applied voltage due topower line :uctuations and the like. Alternatively, an arrangement issuggested in which a triilar winding on the horizontal deflection waveoutput transformer is used to produce the desired pulse voltages and atthe same time provides choke action to keep the horizontal convergencewaves out of the source of vertical convergence waves.

ln order that the practical aspects of the invention may be fullyappreciated, an express embodiment, given by way of example only, isdescribed hereinafter with reference to the accompanying drawing inwhich:

Fig. 1 is a functional diagram of a television receiving apparatus inwhich the invention may be incorporated;

Fig. 2 is a cross section view of a multibeam kinescope of the type towhich the use of the invention is particularly applicable; and

Fig. 3 is a schematic diagram of an embodiment of the invention.

Referring iirst to Fig. l, there is shown a functional diagram ofportions of a color television receiver to which the invention isparticularly adaptable, and which receiver may otherwise compriseentirely conventional circuitry. In such a receiver, color televisionsignals ap pearing at an antenna are applied to a radio frequency waveamplifying circuit and the output therefrom is applied along with theWave obtained from a local beat oscillation generating circuit to afrequency changing circuit. The output of the frequency changing circuitis applied to an intermediate frequency (L-F.) amplifier which may beone having separate channels for picture and sound signals or one inwhich both picture and sound signals are amplified at the same time. Avideo demodulating circuit 17 is connected at terminal 16 to the I.F.amplifying circuit for deriving a video wave from the televisionsignals. The detected video signals are amplified in a video frequency(V.-F.) amplifying circuit 18. Sound signals are derived from the soundI.-F. amplifying circuit, or from the demodulating circuit 17 or fromthe V.F. circuit 18, for further processing in a sound L-F. amplifyingcircuit, an aural signal discriminating circuit, an audio frequency(A.-F.) amplifying circuit and a transducer, usually in the form of aloud speaker. applied to a circuit 19 for converting luminance andchrominance components into proper form for application to the signalinput circuitry of an image reproducing display device, or kinescope 20.The output of the video frequency amplifying circuit is also applied tosynchronizing pulse separating circuit 24 to separate the syn-.chronizing pulses from the picture signals and to separate thehorizontal synchronizing pulses from the vertical. The separatedvertical synchronizing pulses are applied to a vertical deflection wavegenerating circuit 2S and thence to a vertical deflection waveamplifying circuit 26, while the horizontal synchronizing pulses areapplied to a horizontal deflection frequency oscillator and frequencycontrol circuit 27 and thence to a horizontal deflection wave amplifyingcircuit 28. The high voltage and focus voltage generating circuit may becoupled to the horizontal deflection wave amplifying circuit. Thevertical deflection wave amplifying circuit 26, the horizontaldeflection wave amplifying circuit 28 and the high voltage and focusvoltage generating circuit 29 are coupled to the kinescope 20 to supplyvertical and horizontal deflection waves and focus and ultor potentials.The vertical deflection wave amplifying current 26 and the horizontaldeflection Wave amplifying circuit 28 are connected to a convergencewave generating circuit 30 according to the invention for generatingconvergence waves for dynamic convergence of individual beams of themulti-gun kinescope 20. A low voltage power supply, normally connectedto the local A.-C. power lines, is arranged to 1 furnish directenergizing potentials to all circuits. An automatic gain controlamplifying distributing network is coupled to the synchronizing pulseseparating circuit 24 or the video frequency demodulating circuit 17 orto the video amplifying circuit 18 to supply control potentials to thedesired ones of the circuits previously mentioned. Normally the R.-F.and I.-F. amplifying circuits are at least so supplied.

The kinescope 20 may be of the same general type as that disclosed inthe H. B. Law paper hereinbefore mentioned. The kinescope 20 preferablyhas a luminescent screen provided with a multiplicity of small phosphor'areas arranged in groups and capable of producing light ofthe differentcomponent colors when excited by electrons. In back of and spaced fromthe screen there is an apertured masking electrode having an aperturefor and in substantial alignment with each group of phosphor areas. Theluminescent screen and the masking electrode may have planar orpartially spherical surfaces; the invention being equally applicable toeither form of target electrode structure.

The kinescope 20 also has a plurality of electron beams equal in numberto the number of component colors in which the image is to bereproduced. Conventionally, three such electron guns, which may beentirely conventional in structure consisting of a cathode, a controlelectrode and a focusing electrode, are arranged substantially parallel`to\y produce three separate electron beams by which to energizerespectively blue, red and green phosphor areas of the screen of thekinescope.V The kinescope 20 also contains a beam acceleratingelectrode, or ultor, consisting of a conductive wall coating on theinner surface of the envelope of the kinescope and extending out to theregion of the target electrode structure. When these electron beams areproperly converged at the target The output of the V.F. amplifyingcircuit isv structure, the electrons pass through the apertures of themaskingelectr'ode from different directions and impinge on differentphosphor areas of each of the groups so as to produce light in the threecomponent colors. The electrodes of the kinescope 20 may be energized inthe conventional manner and the color information signals are applied sothat the electron beams are modulated in intensity in accordance withthe information carried by the color-representative video signalsderived from the translator circuit 19. The video signal source will notbe described further herein since it does not form an essential part ofthe invention.

Associated with the color kinescope 20 is a deflection system yoke,which may be entirely conventional and in which may be mounted two pairsof suitably placed windings electrically connected so that when properlyenergized, electromagnetic fields are produced to effect angulardeflections of the electron beams in both the horizontal and verticaldirections to scan the usual rectangular raster at the target electrodestructure. Deflection waves for application to the deflection systemwindings are obtained from the vertical and horizontal deflection waveamplifying circuits 26 and 28 respectively.

The beam convergence system in accordance with the invention alsoincludes a plurality of electromagnetic field producing elementsarranged about the neck of the kinescope adjacent to the predeflectionpaths of the electron beams. An example of such construction is shown inFig. 2 wherein three magnet assemblies 31, 32 and 33 arranged about theneck of a kinescope envelope 35. The precise location of the magnetassemblies is not necessarily indicated in Fig. 2 but it is to beunderstood that each of the magnet assemblies is located relative to thepath of one of the electron beams to influence that one beam to thevirtual exclusion of the others. The magnetic fields produced by thesemagnet assemblies are transverse to the associated beam paths and in adirection to move the associated beams radiallyl relative to thelongitudinal axis of the kinescope. The convergence magnet assemblies31-33 are usually energized by a subtantially unidirectional currentcomponent to effect an initial convergence of the electron beamssubstantially at the target electrode structure. Normally, convergenceis initially made at the center of the screen, however, this initialconvergence may be made at any point, for example, at Vonecorner of theraster. In order to do this, the unidirectional energizing currentcomponent is effected in such a way that the magnet may be individuallyenergized in different magnitudes.

The convergence magnet assemblies 31-33 are also dynamically energizedby wave energy derived from suitable generating means so as to effect avariation in the magnitude of the transverse elds produced and to varythe deflection of the individual electron beams as a function of theoverall deflection of the three beams. In this way suitalble variationsare made in the convergence angles between the various beam componentsin theindividual beams so as to produce the desired convergence of thebeams substantially at all points of the target electrode structure. Allof the magnet assemblies being the same, only one will be described indetail. The magnet assembly 31 comprises a core, which may be in onepiece, but is shown in two pieces 36, 37 having legs 38, 39 extending atright angles to the main body of the core. If direct current is utilizedto afford static convergence, the core might conveniently be in onepiece. As shown, however, the core of the magnet assembly 31 is splitinto two pieces 36, 37 and mounted between the core pieces in suitablerecesses formed therein is a swbtantially cylndrical permanent magnet40. This magnet is polarized substantially diametrically so as topresent north and south poles in the two halves thereof substantially asindicated. The permanent magnet 40 may be provided with suitableadjusting facilities, such as a screw driver slot, formed in one or bothends. The rotation of the permanent magnet 40 between the core sections36, 37 enables the strength of the permanent magnetic eld produced tovbe adjusted in both magnetic and polarity. Windings 41, 42 are mountedon the legs of the core pieces, although alternatively the windings maybe wound as a unitary structure and mounted on the main body portion ofthe core. A set of pole pieces 43, 44 is provided internally of thekinescope envelope 35 for each of the convergence magnet assemblies. Theinternal 'pole pieces 43, 44 are arranged to increase the eiectivenessof the associated magnet assemblies by decreasing the reluctance of themagnetic circuit and considerably improving the ux distribution of theeld produced between the pole pieces. The convergence magnet assemblies31-33 produce fields which in the vicinity of the electron beamsassociated therewith are substantially transverse to the axis of thekinescope. The electron beam associated with each of the magnetassemblies may be readily moved toward or away from the longitudinalaxis by adjusting the amount of magnetic ux in the respective assemblies31-33. The direction and magnitude of such beam movement is controlledby the energization of the windings 41, 42 and rotation of the permanentmagnet 40.

The convergence magnet assemblies 31-33 may be energized by means of thecircuit arrangement shown in Fig. 3. The convergence magnet assembliesmay be substantially identical, and may be energized by substantiallyidentical circuits. Therefore, the description will be limited to theparticular circuits by which the windings 41 and 42 of the convergencemagnet assembly 31 are energized, it being understood that the samedescription applies equally as well to the circuits illustrated forenergizing the other convergence magnet windings except Where specicallynoted.

Referring to Fig. 3, synchronizing pulses of vertical deflection rateare applied at input terminals 51, 52 to a vertical deection waveoscillator tube 54 for producing a sawtooth voltage Wave `across acharging capacitor 56 connected in series with a peaking lresistor 57.The peaked sawtooth voltage wave is applied by way of connectionsincluding a coupling capacitor 58 to a vertical deection wave amplifyingtube l59. Vertical sawtooth current waves are induced in a verticaldeection wave output transformer 60 by a primary winding 62 connected inthe -anode circuit of the vertical amplier tube 59. The sawtoothdeflection wave appearing across a `secondary winding 64 is applied to avertical deflection system winding comprising sections 66, 6.7. No Yprovisions are shown in the circuit for deection centering of thescanning beams, but conventional centering current circuitry may beemployed in known manner. A sawtooth voltage wave at horizontal deectionrate is applied at input terminals 71, 72 of the horizontal amplifyingtube 74. A sawtooth current wave isl induced by the connections to theamplifying tube 74 in a winding 76 of the horizontal deliection waveoutput transformer 73. The deection pulse voltage and sawtooth currentwave appearing inthe output portion of the winding 76 is applied to ahorizontal deection system winding comprising two sections 81, v82 thelatter of which is shunted by an antiringing capacitor 83. Again nocentering provisions have beenV shown, but these may be readily suppliedaccording to the known art.

A sawtooth voltage wave at the vertical deflection rate appears acrossan unbypassed resistance element 86 in the cathode lead of the verticaldeection wave amplifying tube 59. This resistance element 86 is'used toreturn the cathode to the point of reference potential, .shown as4ground, and to provide a sawtooth voltage wave for producing thevertical convergence parabolic current wave. An inductance element 88 isconnected ybetween the unbypassed resistance element 86 and a pluralityvof variably tapped Vresistance elements or potentiometers gli, therebeing one such resistanceelement for each circuit desired.

In the example shown, there is a potentiometer 91k for `the redcontrolling electron beam, another potentiometer 91G` 'forthe greencontrollinng electronubeam, vanda further potentiometer 91B for the bluecontrolling kelectron beam. Hereinafter, the suffixes R, G and B aredropped from the reference numerals when considering' the generalaspects of the component circuits, and it should be understood that thedescription with reference by means of a general reference numberapplies equally well to the 'specific component circuits. Due to partialintegration brought about by the *inductance element 88, the potentialacross the parabolic convergence voltage level setting potentiometers 91very closely approximates a parabola. at thel vertical deection rate.Movement of the varms 92 of the potentiometers 91 serves to adjust theamplitude of the parabolic voltage components available for convergingthe individual electron beams in the vertical direction.

By use of the inductor 88 for partiallyvintegrating the verticalsawtooth wave, the expense of a large electrolytic capacitor previouslyused for lthis purpose is eliminated. More important is that the initialoperation and the sta- -bility of the circuit is greatly improvedbecause the manufacturing tolerances of inductors yare closer than thatof electr-oly'tic capacitors. The inductance of inductors does not tendto vary with age, as does the capacitance of electrolytic capacitors.Furthermore the integrating inductor 88 has a negligible effect on theoutput vertical deection wave, which means that a less expensivever-tical output stage may be used Ato secure the ydesired results.

By means of variably tapped Vresistance elements or potentiometers 94R,`94G and l94B connected in parallel across a center tapped secondarywinding 104 of the fvertical vdeflection wave output transformer 60,Apositive or negative sawtooth waveforms lat the vertical deflectionrate may be obtainedby movements of the taps or `arms 9S respectively ofthe resistance elements or potentiometers 94. At an inter-mediateposition of each poten- `tiometer arm, the potential .from the larm tothe neutral point of reference potential, shown as ground, is zero.

Moving the potentiometer ar-m to either `side of neutral causes either apositive or negative sawtooth wave to appear `bet-Ween the ar-m 'and thepoint of reference potential i'of amplitude proportional to the degreeof movement of the arm. Each ofthe .convergence windings is divided intoAtwosections 41, 42 as shown in Fig. 2. Referring again to Fig. '3, theplurality of convergence pole-piece exciting winding sections areindividually connectedy ibetween the arms 92 of the parabola amplitudecontrolli-ng potentiometers- 91 and the arms 95 of the tilt cont-rollingpotentiometers 94, bymeans of a triiilar wound inductofr 100 havingconductors 101-103, a pluralitynof inductors 104R, 104G and 104B. Theinductors 10.0 and 104 are more resistive than `inductive at thevertical frequency as they are intended for operation on the horizontalcurrent components, so that the sawtooth vertical deection frequencyvoltages are unaffected by the horizontal components but are integratedby the substantially high inductance of the convergence system windings41, 42 to produce parabolic current flow. The amplitudes of theseparabolic components are determined by the positions of the arms 92 onthe parabola adjusting potentiometers 91.

A color purity magnet is used with tri-color kinescopes of the typementioned hereinbefore. This magnet operates by directing 'the threeelectron `beams across thellongitudinal yaxis of 'the kinescope and thisbeam movement, together with some component tolerances, makes y'tiltingnecessary. The parabolic waves are tilted, or shifted ls'o that theminimum amplitude points are either toward :the beginning or the end ofthe waves, by positioning the yarms on the sawtooth wave amplitudesetting potentiometers 94. For this reason these potentiometers 94 areusually termed tilt controls. The approximately parabolic verticalvoltages are somewhat still further integr-ated by 4the inductan'ce of`the convergence system 7 `windings'sections and the `inductors104 toyield lthe desired..vertical frequency parabolic current waves.

With tri-colored kinescopes of the type described, the electron guns'aremechanically tilted toward the central `axisof the kinescope so that theindividual beams virtuzally Vconverge at the center of the phosphorscreen. However, -because of manufacturing tolerances, a staticcomponent of magnetic field is necessary to set the beam direction ofeach gun precisely. This field is obtained by means of the rotatablepermanent magnets 40 in the convergence coil assemblies 31 as shown inFig. 2. The field required is a function of the error and the squareroot of the ultor potential, the latter of which follows the power ylinevoltage in shunt tube high voltage regulating systems.

Both the vertical and the horizontal dynamic convergence Yvoltages areapplied to the convergence system windings 41, 42 for alternatingcurrent flow only. When the components of magnetic eld these voltagesproduce are added to the static component required for centerconvergence as previously adjusted, the total field when scauning thecenter of the raster will be in error by an amount equal to .theinstantaneous value ofy the'dynamic convergence voltage. This error iscorrected by adding a compensating field of equal value and oppositesign by means of a resistance element 106 which is connected to a sourceof intermediate potential obtained from the same low voltage rectifierthat supplies the circuits developing the dynamic components; that isthe horizontal and vertical deflection wave translating stages whoseoutputs vary directly with the power line voltage. circuit shown in Fig.3 the compensating field varies in the same manner as the dynamic fieldsso that for normal power line voltage variations, there is high degreeof `tracking over the raster, resulting in excellent beam con- VergenCC.

A voltage pulse wave o f horizontal recurrence rate is applied to aseriescircuit comprising an inductive element and-afresistive elementVof lower impedance than that of the inductive element. Tihelserie-sycombination is .therefore predominately inductive and thevoltage acrossthe series circuit is therefore approximately4 sawtooth in shape, beingan integraloftheapplied pulse voltage. The voltage developed across` the-resistanceelement is similarly `sawtooth in shape". windings in shuntVwith the resistance element, the sawvolta-ge wave is integrated toproduce parabolic current wave through the highely inductivevconvergence systern windings... If the impedance of the convergencesystem winding is'much larger than'thatof the resistance element,thesawtooth voltage wave shape will be but slightly affected.y Byinterposing a compensating capacitive element in the series withtheresistance element, the resulting sawtooth voltage wave will-besymmetrical and slightly S-shaped. This latter arrangement provides amore perfect parabolic current waveform in the convergence winding andpermits the useofY larger values of resistance elements. This resultsin'ilower power loss which is advantageous since the horizontaldeflection frequency power dissipated in the convergence system shows upas `a loss of available regulated high voltage current, which isconventionally derived from the horizontal detlection stage. f i

As Vshown in Fig. 3, a voltage pulse wave of horizontaldeectionlfrequency and positive going with respect to the point ofreference potentiaL'shown as ground, is obtainedby means Vof acouplingcapacitor 107 and applied directlyY across thek variablevinductance Velement 104K which is connected in series with ashuntingresistor 108K In the By placing the convergence system i systemwindings.

anda compensating capacitor 109K. As shown, the horizontal voltagepulse-wave is the same Wave that is conventionally-applied by means of acapacitivey element to the automatic gain control circuit. However, thispulse wave may be-,obtained from any other point in the horizontaldeflection-wave output circuitthat such a gating pulse Wave is obtained.In addition to acting as a choke to prevent horizontal frequencycomponents from entering the source of vertical frequency components,the trifilar winding 100 serves as a pulse wave transformer to inducethe horizontal voltage pulse wave which is im:- presscd across the`winding 101 into the'trilar windings 102 and 103 for application to theother convergence circuits comprising the variable inductance elements104G, 104B. shunting resistors ISG and 108B, and compensating capacitors1096 and 109B. Alternately, an isolated trilar winding on the horizontaldeflection wave output transformerH wouldserve as well and obviate theneed for any coupling'capacitor. Each conductor of the trifilar windingwould still serve as a path form vertical current vcomponents just as inthe choke arrangement. v

-tilted by adding a sawtooth component to the current in vtheconvergence system windings 41, 42 by means Vof tilt controllingcapacitive elements 114. The sawtooth components for the red and greenconvergence system windings 41R, 42K, 41G, 42G are obtained by means ofa coupling capacitor 116 connected tothe trifilar winding 101 of thetrifilar choke 100, while that for the'blue con- .vergence systemwinding is shown with the tilt controlling capacitance element 114Bconnected directly to the trifilar winding 103. Since only capacitiveelements are used, such cross-connections alord many cost reducingalternatives without detracting from the performance of the circuit inany way. The effect of adding the sawtooth component to the parabola isto increase the current on one side of the raster and decrease it on theother. By reversing the sawtooth polarity the action can be reversed.The same type of action occurs if the parabolic current Awave'is shiftedin time with respect to the deflection and blanking period. This iseffected by adding the pulse voltage wave required for tilting to thesawtooth voltage wave used for generating the parabolic wave. 'I'heoverall result is an initially delayed sawtooth voltage wave which uponintegration results in a tilted parabolic wave, requiring compensatingtilt in the opposite direction. The degree of tilt is controlled by theamount of pulse added. The capacitive elements 109, 116, and 114, formvoltage dividers by which the adjustment of the adjustable capacitiveelement 114 in each case determines the amount of pulse added to providethe required tilt. f

Since a horizontal frequency convergence component required by the bluegun of some tri-color kinescopes as conventionally operated is largerthan that required by the red and green guns, the impedance of the blueconvergence system windings 41B, 42B may be made lower so that likevoltages can be used vfor Vthe three dellection In addition the parallelnetwork comprising the capacitor 110 and the shunt resistor v111 may beVadded, as shown, to the blue convergence windings circuit since thestatic compensating current is higher Vdue to the greater dynamicconvergence voltage component. Those skilled in the art will determineVthe values of components to be used in various applications ofthevinvention from the teachings herein, however, the values of pertinentcomponents listed below which were used in a successfully operated colortelevision receiver having are given as' a Rei. No. Component Type orValue Tri-color Kinescope 21AXP22. Convergence system winding:

(red, green (blue only) Vertical oscillator and amplifier tubes. GBL?,Horizontal amplifier tube CD6. Horizontal pulse wave source. 800 toground. Cathode resistor 2 0 o. Vertical Linearity Control. -1 ko.Vertical Integrating Inductor- 2.0 h. Vertical Parabola Control... 0-1ko. Vertical Tilt Contro1. .0-100 o. Vertical Tilt Winding :t100 v.to

ground.

- Trlfilar choke 50 mh.

Horizontal Integrating Inductors.. 100-000 mh Blocking capacitors 50mid. Dropping resistors-- 82 ko. Coupling capacitor. 0.1 mid. Seriesresistors 12 lro. Compensating capacitor 820 mi'. Shunt capacitor (blueonly)- 0.05 mi. Shunt resistor (blue only)- 4700 o. Horizontal tiltcontrol 100-600 mmf. kSeriescapacitor (red and green only) 560 mf.

Power supplied delivered approximately 400 volts between the pointsmarked land ground, with y20() volts being delivered at the intermediatepoints marked +11 The invention claimed is:

l. A beam convergence circuit arrangement for multibeam kinescope theelectron beams of which are deilected in two directions normal withrespect `to each other, includinga plurality of convergence windingsthrough which 'currents of substantially -parabolic waveform offrequency corresponding to electron beam deflection in one of saiddirections are desired, a plurality of series circuits each comprisingan inductance element and a resistance element connected in series,means to apply a voltage pulse train of recurrence rate corresponding tosaid deflection in said one direction across said series circuits, andmeans to couple said windings individually across said resistanceelements in such manner that the voltage produced across each resistanceelement by said pulse train is impressed upon its associated winding.

2. A beam convergence circuit arrangement for multibeam kinescope theelectron beams of which are deilected in two directions normal withrespect to each other, including a plurality of convergence windingsthrough which currents of substantially parabolic waveform of frequencycorresponding :to elect-ron beam deflections in one of said directionsare desired, a plurality of series circuits each comprising aninductance element and a resistance element connected in series, meansto apply a voltage pulse train of lrecurrence rate corresponding to saiddeflection in said one direction across said series circuits, and meansincluding capacitive reactance elements to couple said windings`individually across said resistance elements.

3. A beam convergence circuit arrangement for an internal convergencepole-piece type multi-beam kinescope the electron beams of whicharedeected in two directions normal with respect to each other, including aplurality of convergence pole-piece exciting windings through whichcurrents of substantially parabolic waveform of frequency correspondingto electron beam deilection in one of said directions are desired, aplurality of series circuits each comprising an adjustable inductanceelement and a resistance element connected in series, means to apply avoltage pulse train of recurrence rate corresponding to said deection insaid one direction across said series circuits, and means includingcapacitive reactance elements to couple said windings individuallyacross said resistance elements, the amplitude of sai-d paraboliccurrent waveform being varied by adjustment of said inductance element.

4. A beam convergence circuit arrangement for an inicrnal convergencepole-piece type multi-beam kinescope l0 the electron beams of which aredeflected in two directions normal fwth respect to'each other, includinga plurality of convergence pole-piece exciting windings through whichcurrents of substantially parabolic waveform of frequency correspondingto. electron beam ,deection in one of said directions are desired, aplurality of series circuits each comprising an inductance element and aresistance element connected in series, means to apply a voltage pulsetrain of Irecurrence rate corresponding to said deflection in said onedirection across said series circuits, means including capacitivereactance elements to couple said windings individually across saidresistance elements, and

means to apply a portion of -said'voltage pulse train across each ofsaid windings.

5. A beam convergence circuit arrangement for an internal convergencepole-piece type multi-beam kinescope the electronbeams of which Varedeflected in two directions normal with respect to each other, includinga plurality of convergence pole-piece exciting Iwindings through whichaV current of substantially parabolic waveform of frequencycorresponding to electron beam deilection in one of said ldirections isdesired, a plurality of series circuits each comprising an inductanceelement and a resistance element connected in series, means to apply apulse voltage train of recurrence rate corresponding to said deection in:said one direction across said series circuits, means includingcapacitive reactance elements individually to couple said windingsacross said resistance elements, and means including other capacitivereactance elements individually operative to conjunction lwith the rstsaid capacitive reactance elements to apply a portion of said pulsevoltage train individually to ysaid windings. v

y6. A bea-m convergence circuit arrangement for an internal convergencepole-piece type multi-beam kinescope the elect-ron beams of which aredeflected in two directions normal with respect to each other, includinga plurality of convergence polepiece exciting windings through which acurrent of substantially parabolic waveform of frequency cor-respondingto electron beam deection in one of said directions is desired, a.plurality of series circuits each comprising an adjustable inductanceelement and a resistance element connected in series, means to apply apulse voltage train olf recurrence rate corresponding to said deflectionin said one direction across said series circuits, means includingcapacitive reactance elements individually to couple said windingsacross said resistance elements, and means including adjustablecapacitance elements individually operative in conjunction with the rstsaid capacitive reactance elements to apply a portion of said pulsevoltage train individually to said windings, the amplitude of saidparabolic current waveform being varied by adjustment of said inductanceelement and the tilt being varied by adjustment of rsaid capacitanceelements.

7. A beam convergence circuit arrangement for an internal convergencepole-piece type multi-beam kinescope the electron beams of which aredeiiected in two directions normal with respect to each other, includinga plurality of convergence pole-piece exciting windings through whichcurrents of substantially parabolic waveforms of frequency correspondingto electron beam deection in both `of said directions are desired, aplurality of series circuits each comprising an inductance element and aresistance element connected in series, means including a trilar windingindividually to apply a voltage pulse train of recurrence ratecorresponding to said deflection in said one direction across saidseries circuits, means including capacitive reactance elementsindividually to couple said windings across said resistance elements,means includingadjustable capacitive reactance elements to apply aportion of said voltage pulse train across said windings, an inductivereactance element and a plurality of variably tapped resistance elementsconnected in common to said inductive reactance element, means to applya sawtooth wave of recurrence rate corresponding to il deflection in theother direction between said inductive reactance element andv each ofsaid variably tapped resistance elements to produce asubstantially'parabolic voltage wave across the last said elements, aplurality of variably tapped resistive elements having taps individuallyconnected to said triiilar winding, means to apply a pulse trainrecurrence rate corresponding to deflection in said otherdirectionsacross said resistive elements, and means coupling said convergencewindings to the taps of said A variably tapped resistance elements.

8. A beam convergence circuit arrangement for a multibeam kinescope,comprising a vertical deflection wave circuit including an outputtransformer having a convergence winding with an intermediate tap -beingelectrically at a point of xed reference potential and midway betweenthe terminals of. said winding, and an amplifying electron dischargetube having anode and cathode electrodes connected to the primarywinding of said transformer through an unbypassed resistance element, aplurality yof variably tapped resistive elements connected between saidterminals of said convergence winding, an inductor having one terminal`connected to the one terminal of said resistance element, a pluralityof variably tapped resistance elements connected :between the otherterminal of said inductor and said point of fixed reference potential, ahorizontal deflection wave output transformer having a winding, a trilarchoke having plurality of conductors having terminals connectedindividually to the taps of said resistance elements and being coupledto a point on said horizontal transformer winding, an adjustableinductor, a resistor and a capacitor connected in series with each ofthe conductors of said tritlar choke, adjustable capacitors connectedacross each of the series vcircuits comprising said adjustable inductorand resistor,

lil

a plurality of convergence system windings connected individuallybetween junctions of said adjustable inductors and resistors and thetaps of said resistance elements by blocking capacitors, connectionsbetween each of said capacitors in said series circuits and thejunctions between said blocking 'capacitors and said convergencewindings, and resistors connected between a point of fixed energizingpotential and the individual junctions `of said blocking capacitors andsaid convergence system windings.A

9. A beam convergence circuit arrangement for multibeam kinescope theelectron beams of which lare deected in two directions normal withrespect to each other, including a plurality of convergence windingsthrough which currents of substantially parabolicV waveformbf frequencycorresponding to electron beam deflection rin one of said directions aredesired, a plurality of series circuits each comprising an inductanceelement land a resistance element connected in series, means to apply avoltage pulseftrain of recurrence rate corresponding to said deflectionin said one direction across said series circuits to producesubstantially sawtooth voltage waves `zacross said resistance elements,and means to Icouple said windings individually across said resistanceelements in'such manner that said sawtooth voltage Waves 5appearingacross vsaid resistive elements serve to induce substantially paraboliccurrent waves in said windings.

References Cited in the le of this patent UNITED STATES PATENTS

